HOOF PROBLEMS

LESSON FOUR

When considering hoof problems, we don’t know the exact number of possible causes of disease and pain. We do know there at least 30 different causes of pain that affect only the back one-third of the foot. Imagine the complications for diagnosis when you consider just the known causes in various combinations.

With our technological advancements for diagnosis, most of the time both diagnosis and treatment are “best guesses.” It is no wonder so much controversy surrounds the trimming, shoeing and health care management of the horse’s hoof.

Most horsemen, veterinarians and horse shoers agree, in 9 out 10 cases of lameness, there is a direct or indirect relationship to poor hoof care, poor hoof form or hoof disease. With all the possible combinations of treatments, from “natural hoof trimming” to “corrective or therapeutic shoeing” the single approach with the highest probability for success is “bringing the hoof into balance for the individual horse.” (See Lesson Three for hoof balance definitions. See www.naturalangle.com/ for feature articles on hoof care and shoeing.)

One of the major contributors to hoof problems is the unconditional acceptance of “traditional perimeter shoeing” which calls or the shoe to be applied to fit the perimeter of the hoof after the hoof has been trimmed. Make the shoe fit the hoof is the credo of the perimeter shoer. Such shoeing allows the hoof deformities to remain and in most case become even more severe. Such trimming allows existing deformities to continue.

Not understanding the horse’s hoof, most horse owners want to see a “nice smooth shoeing job” where the shoe and the foot match exactly. Tending to want to please their customers, the shoer provides such a job, giving little or no thought to “bringing the hoof into balance” if it requires correcting hoof deformities by the use of extensions.

Observations of the hoof should allow the shoer to know how to apply the shoe in such a manner as to achieve hoof balance. The shoe should be the “balanced hoof” correcting the deformities. If may not be pretty, but it corrects hoof problems, and it is what should be demanded of the shoer by the knowledgeable horse owner.

This lesson presents the most recent “positive result verification” opinions and recommendations for the care and/or treatment (including trimming and shoeing) of the most commonly seen hoof problems and diseases. (Sheared heels will not be addressed in this lesson. For information on sheared heels, see www.equipodiatry.com/shearhls.htm )

HOOF HEALTH SUPPLEMENTS

There are dozens of supplements suggesting they will help produce healthy hooves. Whether their claims are true or not often depends on what you want to believe. For example, many veterinarians suggest biotin for hoof growth, yet there is no scientific evidence that biotin supplements are effective. In fact, the evidence is quite to the contrary; tests show biotin supplements have no affect on hoof growth.

If you have a nutritionally unhealthy hoof, then some supplementation of nutrients may be helpful in restoring health.

The hoof grows from the coronet band down and takes about a year to produce a new hoof. Note on your calendar when you started feeding a supplement and then monitor the hoof. If the supplement is going to be of benefit, you’ll see a line of healthy new hoof growing down from the coronet band—this indicates the horse is utilizing the nutrients in the supplement. If you don’t see recognizable improvement, then nutrition is not causing the poor hoof quality, so supplements are not going to help.

Environment, exercise and genetics play a major role in healthy hoof growth. If you are feeding good quality feed, feeding according to the manufacturer’s directions (weigh your feed; don’t feed by scoops or flakes), providing free choice salt and plenty of good quality forage, your horse probably doesn’t have nutritional issues.

LONG TOE, LOW HEELS

The most frequently seen hoof deformity is the long toe and low heel and according to the latest research (2004) these are not related.

Horses with collapsed or under-run heels tend to “stumble,” and it has always been the assumption this was caused by excessive toe length.

“Time to re-shoe,” was the response. “Cut the toe off, set the shoe back, use a square-toed shoe.” Those were the recommendations along with “round the toe for quicker break-over, or use a ‘natural balance shoe’.”

One of the ways it was thought to ease break-over was use of the squared toe shoe. For the past decade this has been a popular choice for shoers, and one that horse owners have never protested. However, the Royal Veterinary Academy studied squared toe shoes and how they affect break-over and movement and after two years of research announced in 2004 that the shoes have “no affect on break-over or movement whatsoever on the sound horse.”

The latest research shows that “discrepancies of mechanical support provided by the heel” are the cause of support failure, stumbling and subsequent heel deformation. Failure of support during the load acceptance (foot on ground) in turn results in support failure during force application (lifting of the hoof)--the energy required to efficiently propel the horse.

Randy S. Luikart explained it this way at the Third Annual International Hoof-Care Summit (2005): the horse’s movement requires the foot and leg to operate mechanically in two roles, load acceptance and load application. The horse requires support for load acceptance and “additional” support for load application.

Imagine it this way—if I hand you an anvil, you have no idea how heavy it is until you feel it. Once you feel it, you can determine if you can hold it, or must drop it. If you can hold it, and then I tell you to “throw it,” you immediately recognize it will take “additional” force to throw it.

It is easy to understand that it is easier to stand still and hold the weight than it is to throw the weight, Luikart explained. In both cases, the support for load acceptance (holding) and load application (throwing) must be adequate or the limb will fail in its purpose—performance.

It is now understood that the horse with the under-run heel does not have adequate support for “load application.” It is not the long toe that is the problem, but the lack of heel support to facilitate “load application” or the movement of the hoof.

Failure to shoe for adequate heel support is the cause of the under-run heel, not a long toe. (If we do not consider shoeing, then it is the pastern joint mechanics and the heel’s failure to support those mechanics that cause the under-run heel.)

To determine how far back the shoe must extend to properly support the heel you must return to analysis of the balanced hoof. (See lesson Two See www.equineoz.com.au/art14.htm )

Run you fingers down the center of the cannon bone to the center of the fetlock joint—this point is pretty close to the center of rotation of the joint and a perpendicular line dropped to the ground from this point will indicate the “approximate place where the end of the shoe should reach.” I say the “approximate place” because the shoe must actually extend a bit farther, a distance you will have to estimate. When the horse in motion puts his foot down, load acceptance is established as body mass travels over the foot. At this point, the fetlock joint will flex downward approximately 12 degrees, moving the center of the fetlock joint backward. The end of the shoe should extend to that farthest backward point which will always be just behind the bulb of the heel.

Any shoe shorter than the bulb of the heel will not provide enough support for the load acceptance which in turn creates the failure of support for load application, causing the heel to collapse and the horse’s movement to be inefficient.

Shoes which only reach the end of the hoof wall at the heel are inadequate and will start or exacerbate the low heel problem. The shoe length must remain correct throughout the entire shoeing period if any heel recovery is to be expected.

Infrequent shoeing is a contributing factor to the low-heel problem, since toward the end of the shoeing period, heel support is being reduced by natural hoof growth. The average horse grows hoof quickly enough to require shoeing every 30 days if the hoof is to remain within satisfactory limits of hoof balance.

The long toe, low heel problem cannot be corrected by rasping the toe length or moving the shoe back. Rasping the toe length weakens the hoof wall, and in combination with moving the shoe back creates greater heel weight bearing, thus collapsing the heels even more.

Wedge pads to artificially raise the heel are not a solution; in fact, in most cases they increase the problem by crushing the heel hoof wall farther under the foot and pushing the horn tubulars in to a more horizontal position.

NAVICULAR (CAUDAL HEEL SYNDROME)

“Navicular disease or problems”, or as it is more popularly referred to by veterinarians today, “caudal heel syndrome”, can begin showing symptoms in horses as young as two years old.

There is little doubt the cause of these problems is due to infrequent and/or improper trimming and/or shoeing which restricts the still developing coffin bones and sensitive inner hoof structures, starving them of vital circulation and movement.

Older horses suffer the problems when their hooves are constricted and then stagnant in function due to shoes too small, or shoes improperly applied. In essence the hoof is being jammed and stuffed into a “steel box” from which there is no relief. This is a major factor in the creation of “contracted heels” always seen in caudal heel syndrome.

The picture shows contracted heels with a buildup of excessive sole.

(Click here to see picture.) Note how there is greater heel depth on the left side of the hoof. (Click here to see the hoof after trimming.)

The hoof is by nature dynamic. When it is not allowed to move in intended functions, it becomes deformed which eventually leads to pain and often debilitating lameness.

There is no single shoeing protocol other than attaining “hoof balance.” And there is no “quick fix.” There are many opinions on how to shoe the navicular horse.

Allowing the horse to remain barefoot for several months while getting plenty of exercise on firm ground may be the best first step toward establishing a better-shaped hoof. Applying a shoe to the foot using the techniques of side extensions, wide heel width, extended heels and no heel nailing, allows the hoof’s dynamics to create a balanced shape. The horse must receive consistent and extensive exercise on firm ground.

Horses should be trimmed and/or shod every 30 days. The idea of shoeing and /or trimming in six or eight week intervals is a contributing factor in hoof deformities since the hoof simply experiences too much growth.

This shoe extends beyond the perimeter of the hoof wall and well beyond the heels creating a balanced foot. The shoe provides plenty of width to allow the foot to expand. (Click here to see picture.)

Drugs such as isoxsuprine and phenylbutazone do nothing to improve the deformed hoof.

Eggbars and reversed shoes may give more heel width and support providing the opportunity for the hoof to return to a more balanced shape.

Special pads, wedges and impression material have no therapeutic value and in the long run may actually be more damaging by creating further deformities.

According to Dr. Tomas Teskey, performing digital neurectomies (heel nerving) promotes further degeneration of the entire lower leg and hooves. “Instead of cutting the nerves to a part of the horse’s anatomy and achieving a completely false sense of soundness, it is better to attain correct hoof form and thus proper and vital physiologic function.”

SAND CRACKS

There are three “named” types of hoof cracks.

A “sand crack” originates at the coronary band and continues toward the toe of the horse, running parallel to the horn tubules, either completely or partially to the edge of the hoof. These cracks can be thought of as a fracture of the hoof wall.

A “horizontal crack” is parallel with the coronary band and grows out with the hoof.

A “grass crack” originates toward the toe and runs parallel to the horn tubules toward the coronary band. These cracks can be thought of as a “split” in the hoof wall.

Cracks are identified by location, and are called toe, quarter or heel cracks. On the bottom of the foot, or solar aspect, cracks usually go across the bar or sole and radiate from the apex of the frog, and then are called, “bar” or “sole” cracks.

Cracks which only penetrate the outer insensitive horn are not usually painful, but can become deep if neglected.

Deep cracks penetrate to the sensitive laminae, often bleeding during exercise, and can become infected and generally cause lameness.

Sand cracks result from uneven stress on the hoof capsule caused by foot imbalance, shoe fit and the surface worked upon and the speed during exercise.

Horizontal cracks originate either from trauma to the coronary band or where an abscess has broken out at the coronary band. Horizontal cracks are usually no problem unless they interfere with nailing.

Grass cracks are caused by poor hoof quality, infrequent shoeing in which the hoof wall overgrows the shoe or seedy toe (white line disease). Superficial and even deep grass cracks can usually be trimmed out in routine foot dressing. Flares must be removed and the hoof wall should be made straight or exhibit only a very slightly convex line.

Scoring the hoof wall above the cracks is common, but is ineffective and tends to weaken the hoof wall.

If seedy toe is involved, the area must be cleaned out completely and left open whenever possible.

Toe sand cracks are generally associated with hoof imbalance. The first step in treatment is to correct the hoof balance. Usually the toe is too long and should be trimmed, while the new shoe must provide adequate heel support.

After the foot has been trimmed, dorsal concavity should be removed with the rasp, and then the shoe should be fitted.

Heel and Quarter cracks generally have the same cause (medio/lateral imbalance) and require the same treatment.

Priority must be given to the correction of the imbalances that generally start with a limb imbalance. The limb imbalance cannot be corrected, so he hoof must be balanced to accept and reduce the stresses in the hoof wall.

The solar plane of the foot must be balanced at 90 degrees to the long axis of the cannon bone. A bar shoe gives stability to the foot and should be fitted symmetrically on the foot with each side equidistant from a line through the apex of the frog. Aligning the shoe in this manner will generally create the “required shoe extensions” needed to bring about medio/lateral balance.

Hoof crack repair is known as patching, and there are many ways to patch a crack. The key is that the patch must be strong, safe to apply and durable. Most horse shoers, working with a veterinarian, will have the materials to patch.

Always keep in mind that without correct balancing ad shoeing, the most elaborate of patches will be ineffective.

THE CLUB-FOOT

One of the most difficult hoof problems to manage for veterinarians and horse shoers is the club-foot.

The condition affects all breeds and ages, and the condition can be attributed to numerous causes with the start of “clubbing” beginning as early as one month of age.

Because the club- foot is so common and so difficult to correct, it has been the subject of clinical research, testing and a good deal of trial and error treatment. Experts have examined and studied the club foot from a nutritional, mechanical, genetic and anatomical view, and have developed treatments which allow even horse’s with severe cases to lead productive lives. Treatments range from trimming and shoeing to surgical techniques.

A foot is considered “clubbed” anytime the hoof angle is steeper than the pastern angle. Many veterinarians and shoers define the clubbed foot as having an angle steeper than 60 degrees.

There are varying degrees of the club-foot. The mildest would have the pastern and hoof angles just slightly out of line…the worst occurring when the hells have been pulled upward off the ground by the deep flexor tendon.

A good level lateral radiograph (X-ray) will show some remodeling of the tip of the coffin bone on most club-feet. This deformation is caused by the fact the club-footed horse is walking, more or less, on the tip of the bone. This added pressure causes the vertical distance between the bone and sole to be next to nothing. There will be very few cases that don’t show this club foot symptom.

In this lesson we are only looking at a very few treatments; most effective for the mildest cases. Severe cases are going to require teamwork between veterinarians and shoers and will require consistent attention for an extended period of time.

Veterinarian and “shoeing” expert Ric Redden has developed a grading system for club- feet.

The key to successful treatment, says Dr. Redden, is early attention. “Treating an early stage club foot increases the odds of preserving bone integrity and health of the soft tissue growth centers,” Dr. Redden says.

Veteran horse shoer Thomas Breningstall says in comparing horses with club-feet to normal horses, he has found that every club-footed horse has a weak shoulder on the side of the club foot, making the leg shorter. Recognizing this problem, Breningstall offers six tips for correcting club-feet.

1. In young horses with a predisposition of body imbalance, Breningstall says they hold the weaker, shorter leg back while feeding off the ground. They rest the toe of the foot on the ground while the stronger, longer side holds the body weight and becomes even stronger. Breningstall says you can help the young horse by not feeding on the ground, instead feeding from raised mangers or hay bags.

2. Breningstall puts an extended toe shoe on the club-foot and leaves the other foot bare. If he cuts the heels down on the club-foot, he adds a leather pad with the shoe to raise that side of the horse up again.

3. As the foot grows, he keeps the club-foot longer—both toe and heel—than the opposite foot. After several months, he says he can put a normal flat shoe with pad on the club-foot and not use an extended toe.

4. Many horses can go barefoot, says Breningstall, once the club-foot has grown longer than the other foot. He says the shoulders will even out, especially if the horse gets more exercise on the clubbed-foot side.

5. Breningstall says do not use a wedged pad. A wedge pad on the heel causes the coffin bone to rotate farther. If the wedge is used on the toe, too much strain is placed on the laminae and tendons and the technique over-corrects the problem.

6. Use the same therapy on adult horses with limited use of the extended toe shoe. He says you can often “rocker” the toe to reduce stumbling which is seen more often in older horses.

According to Breningstall cutting the inferior check ligament, or any tendon may help the horse, but it also may not---I’ve seen horses maintain the club-foot since the surgical technique does nothing to improve the horse’s “imbalance.”

Breningstall’s theory concerning “stance” of young horses trying to graze is supported by shoer Larry Davis who says he is convinced that “stance” is a major contributing factor to club-feet.

The young horse which develops a club-foot will not alternate his stance and constantly grazes with the same foot back in a recessive position. The foot that is back grows less toe and more heel, while the opposite foot grows lots of toe and less heel.

Both shoers say foals should not be grazed on short pasture and that abundant amounts of forage offered in an elevated position will slow or eliminate the creation of clubbed feet.

LAMINITIS

The definition of laminitis is inflammation of the sensitive laminae within the hoof. Laminae are the connective tissues between the hoof wall and coffin bone.

Laminitis and founder are not the same. Founder occurs when the laminae tissues die allowing the coffin bone to drop or rotate. Laminitis does not always lead to founder.

There are three distinct stages of laminitis: developmental, acute and chronic.

DEVELOPMENTAL: This is the period when something occurs to the horse or pony leading to the inflammation of the laminae.

There are many known causes, many unknown and occasionally laminitis appears with no apparent cause.

A few of the most common causes are:

1. Overloading the digestive system with carbohydrates and

starches; overfeeding grain, lush pasture or rich hay

are a few examples. This is the most recognized cause of

laminitis.

Horses diagnosed with Cushing’s syndrome, Equine

Polysaccharide Storage Myopathy, abnormal thyroid

levels or are insulin resistant must be offered diets

which avoid carbohydrates and starches.

· Learn how to feed horses properly by taking the

course “Nutrition for Maximum Performance

2. Obese/overweight condition.

3. Retained placenta.

4. High fever.

5. An allergic reaction to a vaccine or medication.

6. Exposure to black walnut shavings.

It is sometimes very difficult to recognize a horse in the developmental stage of laminitis. Observation and awareness is the key.

It is recommended as part of the daily routine to check the horse’s digital pulse and hoof temperature. If either is elevated now is the time to apply ice and start preventative treatment. (Click here to see location of digital pulse.)

Research has shown applying ice to the hooves during the developmental stage of laminitis may prevent the onset of the acute stage. Dr. Chris Pollitt, researcher for the University of Queensland, Australia, recommends the horse stand in ice 20 minutes twice a day with the time being extended to one to two hours depending on the severity of the condition. During research horses have stood in ice for 2 days straight with no detrimental effects. (Click here for more information on laminitis research.)

The developmental stage may last 12 – 50 hours depending on the cause.

ACUTE: After the developmental stage the horse may enter the acute stage. This is when the first signs of hoof pain occur and many people first realize something is wrong. Elevated hoof temperature and bounding digital pulse may be apparent. The coronary band may be swollen and distended. The horse may stand in the classical laminitis stance of front legs extended trying to relieve pressure on the toes.

X-rays of the hoof should be taken at this point. They will serve as a baseline for future x-rays, show if the coffin bone has rotated from a previous laminitis episode and allow a measurement be taken of the distance between the dorsal hoof wall and the dorsal cortex of the distal phalanx. If the coffin bone shows severe rotation at this early stage of laminitis the prognosis is poor.

Treatment during the acute stage of laminitis is aimed at alleviating pain and minimizing further damage to the hoof.

The use of anti-inflammatory drugs (NSAID’s) to make the horse more comfortable is usually recommended. Phenylbutazone (bute) appears to be the most effective drug. Care must be taken the horse is not made too comfortable and moves around excessively – causing more damage to the hoof. The dose used should take the edge off the pain and give him some relief.

The attending veterinarian may recommend a vasodilator agent, but research has not proven these drugs effective treatments in laminitis.

Most veterinarians will recommend the horse be confined to a stall and the shoes be pulled. These steps will lessen further trauma to the already weakened laminae.

The common mechanical treatment of the hoof is aimed at aiding break-over, elevating the heel in order to decrease the force on the deep digital flexor tendon and supporting the palmar/plantar (digital cushion) part of the foot.

Dr. Stephen O’Grady, farrier and veterinarian from the Northern Virginia Equine Facility (http://www.equipodiatry.com), recommends the following treatments be implemented.

To remove the stresses placed on the laminae at break-over, a line is drawn across the solar surface of the foot approximately ¾ inch dorsal to the apex of the frog. The hoof wall and sole are beveled at a 90 degree angle dorsal to this line using a rasp. This effectively decreases the bending force or lever arm exerted on the dorsal laminae. It also moves the break-over point back. Heel elevation and support can be applied in one of three ways.

1. Sand is a readily available, inexpensive and often-effective

form of foot support. It provides even support over the entire

solar surface of the foot, and it allows the animal to angle its

toes down into the sand, thus raising the heels and changing

the angle of the fetlock.

2. The use of 3-inch high-density industrial Styrofoam has gained

popularity as a form of foot support. When applied to the foot,

the weight of the horse crushes the Styrofoam, forming a

resilient mold in the bottom of the foot. It is easy to apply, is

very forgiving, and it provides heel elevation and good ground

support. Additional heel elevation can easily be fabricated.

Once the horse has crushed the original piece of Styrofoam,

this piece is cut in half and the palmar half is retained and

used as a heel insert. Another full sized piece of Styrofoam is

applied underneath it.

3. The third method utilizes a commercially available combination

of two 5-degree wedge pads that are riveted together, along with

an attached cuff so they can be taped to the foot.

These wedges are combined with a resilient silastic material

placed in the bottom of the foot for support. This method is

used on horses that have underrun heels, a broken hoof

-pastern axis or radiographically show a negative heel angle

(the solar margin of P3 is lower at the heels than at the toe on

the lateral radiograph). To apply this method, fill the bottom of

the foot with dental impression material, hold the foot up until

the impression material sets, place the foot in the wedges and

tape in place. This method provides the best heel elevation. All

of the above support methods are easy to apply, provide firm,

but forgiving support and allow easy removal to examine the

bottom of the foot. They also provide uniform support to the

frog, sole and bars in the palmar/plantar two-thirds of the foot.

This is accomplished without causing local ischemia and

pressure necrosis which may occur if treatment is reliant on

frog support alone.

The acute stage lasts until the horse recovers or enters the chronic stage of laminitis.

CHRONIC: Not all horses will enter the chronic stage of laminitis. Research has shown only 15 to 20 percent of the horses in the acute stage will progress to the chronic stage – if proper treatment was implemented at the developmental and acute stages.

The chronic stage is when the laminae have died allowing the distal phalanx (also known as the coffin bone, pedal bone or P3) to drop or rotate downwards. The signs usually exhibited by the horse are persistent lameness, mechanical collapse of the foot, abscesses, and deformity of the hoof wall. The horse is now foundered (the coffin bone is sinking.)

The treatment goal is to realign the displaced coffin bone; a goal usually unattainable. Corrective trimming and shoeing are the common methods used. Dr. O’Grady has had much success with the use of glue-on shoes. (http://www.equipodiatry.com/chronlam.htm) More radical surgical treatments, such as accessory ligament desmotomy or deep digital flexor tenotomy may be attempted. Each case is different with different results, so the treatment of choice may vary.

The chronic stage can last indefinitely.

ASSESSMENT OF PAIN: Trying to decide what degree of pain the horse is experiencing may be difficult at times. The use of the Obel grading system can help.

• Obel Grade 1 – The horse shifts his weight from one leg

to the other. Lameness is not noticed at the walk.

But, while trotting the horse is stiff and noticeably “off”.

• Obel Grade 2 – The horse is stiff and “off” at the walk

and trot. He will allow his feet to be picked up without

the opposing foot showing soreness from having to bear

extra weight.

• Obel Grade 3 – The horse is very stiff, reluctant to

move and is uncomfortable when asked to support

his weight on one foot when the opposing foot is

being picked up.

• Obel Grade 4 – The horse exhibits severe lameness.

He refuses to move unless forced and tends to lie

down much of the time. His feet cannot be picked up.

Assignment:

Send your report and photos to: cathyhansonqh@gmail.com Please put “Lesson 4 Report” in the subject line.

1. Take two pictures of your horse’s front feet (side and rear view). Write a brief report assessing the “balance of the foot.” Is this horse shod properly, or are there corrections that need to be made?

2. Write a brief report about any of the following with which you may have had experience (include treatments and results): navicular, clubbed-feet, sand cracks, laminitis, under-run heels.